Don’t erroneously optimize out lda instructions in certain cases involving instructions the native-code optimizer didn’t know about.

This could cause problems when asm blocks contained instructions that the ORCA/C native code optimizer didn’t know about, as in the example below. It might also be possible to trigger this bug without asm blocks (particularly with the large memory model), but I haven’t run into a case that does.

The new approach conservatively assumes that unknown instructions block the optimization. This should be equivalent to the old code with respect to the instructions defined in CGI.pas, except that m_bit_imm should have been treated as blocking the optimization but was not. There are still some other potential problem cases with applying this lda-elimination optimization to arbitrary assembly code, but fixing them might interfere with the optimization in useful cases, so I’m leaving those alone for now.

Here is an example of a program with an asm block affected by this problem:

#pragma optimize 74
int x,y;

/* should print 2 when invoked with argc==1 */
int main(int argc, char **argv)
{
    x = argc;
    y = argc + 6;

    asm {
        lda #1
        pha
        eor >x
        bne done
        inc argc
done:   pla
    }

    printf("%i\n", argc);
}

Native.pas

@@ -1374,16 +1374,15 @@ var
             ASafe := true;
             goto 1;
             end {if}
-         else if opcode in
-            [m_adc_abs,m_adc_dir,m_adc_imm,m_adc_s,m_and_abs,m_and_dir,
-             m_and_imm,m_and_s,m_asl_a,m_cmp_abs,m_cmp_dir,m_cmp_dirX,m_cmp_imm,
-             m_cmp_long,m_cmp_s,m_dea,m_eor_abs,m_eor_dir,m_eor_imm,m_eor_s,
-             m_ina,m_lda_abs,m_lda_absx,m_lda_dir,m_lda_dirx,m_lda_imm,
-             m_lda_indl,m_lda_indly,m_lda_long,m_lda_longx,m_lda_s,m_lsr_a,
-             m_ora_abs,m_ora_dir,m_ora_dirX,m_ora_imm,m_ora_longX,m_ora_s,
-             m_pha,m_sbc_abs,m_sbc_dir,m_sbc_imm,m_sbc_s,m_sta_abs,m_sta_absX,
-             m_sta_dir,m_sta_dirX,m_sta_indl,m_sta_indlY,m_sta_long,m_sta_longX,
-             m_sta_s,m_tax,m_tay,m_tcd,m_tcs,m_xba,m_tsb_dir,m_tsb_abs] then
+         else if not (opcode in
+            [m_clc,m_cop,m_cpx_abs,m_cpx_dir,m_cpx_imm,m_dec_abs,m_dec_absX,
+             m_dec_dir,m_dec_dirX,m_dex,m_dey,m_inc_abs,m_inc_absX,m_inc_dir,
+             m_inc_dirX,m_inx,m_iny,m_ldx_abs,m_ldx_dir,m_ldx_imm,m_ldy_abs,
+             m_ldy_absX,m_ldy_dir,m_ldy_dirX,m_ldy_imm,m_pea,m_pei_dir,m_phb,
+             m_phd,m_phx,m_phy,m_php,m_plb,m_pld,m_plx,m_ply,m_plp,m_rep,
+             m_sec,m_sep,m_stx_dir,m_stx_abs,m_sty_abs,m_sty_dir,m_sty_dirX,
+             m_stz_abs,m_stz_absX,m_stz_dir,m_stz_dirX,m_tsx,m_txs,m_txy,
+             m_tyx]) then
             goto 1;
          end; {for}
 1: